Hydrographic Surveying

Hydrographic surveyors practice the science of measuring and describing the physical features of rivers, lakes, and oceans. Hydrographers survey and chart waters for navigation, determine water depth and measure tide currents. Hydrographic applications include the preparation of navigational charts, tide and current tables, sailing directions and related publications for commercial, industrial and recreational use.

Hydrographic surveys are conducted from a moving platform where depth, time, date and position are collected, collated and recorded. Onboard navigation, differential GPS and data logging systems ensure that the survey vessel follows predetermined tracks to give appropriate coverage of the survey area as depth soundings are recorded.

Hydrographic surveys are required for the production of nautical charts, which are graphic portrayals of the marine environment and are essential for safe navigation. They are used to define courses and navigate ships and boats by the shortest and most economically safe route. Hydrographic surveyors compile sounding information, climatology, water clarity data, tidal information and past survey data when preparing a nautical chart, which shows the nature and form of the coastline or shoreline, the depths of the water and general character and configuration of the sea, lake or river bottom. Locations of dangers to navigation, the rise and fall of the tides, locations of man-made aids to navigation, and the characteristics of the Earth's magnetism may also be noted.

Hydrographers also conduct surveys for dredging and construction projects, submerged pipeline and cable crossings, location of wrecks, and maritime boundary delineation. On a national scale, the Canadian Hydrographic Service (CHS) is responsible for surveying Canadian navigable waterways, and for producing a number of nautical publications, including nautical charts in both paper and digital formats, sailing directions, bathymetric maps, tide and current tables and other related publications.